Safety Alerts 8

Fired Equipment

• Incinerator: Do not externally insulate hot casing of incinerator/ firebox. Casing can get red hot and fail. Use Personnel Protection Mesh instead

• Incinerator: Inadvertent water addition into methyl mercaptan caused hydrate blockage in winter. Operators tried to clear it by spraying hot water on the piping and venting to an incinerator. This resulted in high pressure alarm in the vent line to incinerator in another section of the plant. Operators in that section of the plant assumed liquid blockage in their line to incinerator and attempted to drain it. Liquid mercaptan drained, vaporized. 24 tons released. Fatalities. [Potential hydrate forming chemicals: Hydrogen Sulphide, Acetylene, Methyl Mercaptan, Chlorine, Vinyl Fluoride, Carbon Dioxide, Ethylene, Methane, Ethane, Natural Gas, and other Hydrocarbon gases]

• Incinerator: 2 incidents in Phthalic Anhydride (PA) plant incinerators. (1) Feed gas preheated by flue gases. Internal rockwool insulation installed in the feed gas duct to incinerator soaked up with PA that exploded. Duct work replaced with SS piping. Switched to external insulation (2) PA accumulating at the inlet of Feed Preheater (Recuperator) moved thru it during start-up and exploded at the outlet

• Incinerator: 3 explosions. (1) Combustibles accumulation in the feed drum during start-up resulted in an explosion at the outlet of Slurp cum Start-up Air blower (2) While switching from Caustic Scrubber back to Incinerator, incinerator hot gases travelled via a leaking valve to feed gas flowing to Caustic Scrubber and (3) Similar to 2

• Coal fired boiler: Clinkers formed and bridged / blocked ash outlet, that led to ash build-up and firebox pressure build-up. While rodding out the clinkers, firebox high pressure trip was bypassed. Resulted in firebox pressure fluctuation. Unburnt coal particles were carried into convection/ economizer section that resulted in secondary combustion and high temperature. Blast in the economizer resulted in hot gas, steam and ash release. Burn injury to 300 odd persons

Pumps

• Remote waterflood facility pump plunger broke (blocked outlet?) releasing H2S laden water. Pump was not electrically isolated. H2S detectors were not regularly tested and didn’t alarm. Personal H2S detector was not used. Pumper fatally injured. Better ventilation of pump house or openair installation of pumps

• Common spare pump serving 2 different services may save a little money. But inadvertent wrong line up + inability to trip the pump on LALL/ PAHH can cause accidents and losses

• Reverse rotation: On power failure, Delayed Coker feed pump reverse rotated due to malfunction of its discharge check valve, under discharge pressure + 30 bar BFW injected to furnace coil to purge it. Pump and its motor damaged. Consider remote operated discharge valve for bigger pumps 

• Pumps are involved in a number of major fire/ explosion incidents as they can spray liquids onto hot surfaces or create vapor cloud when pumped liquids flash

• Pump Seal related accidents: (1) using a redundant pump with seal not suitable for the pumped fluid or (2) nature of pumped fluid has changed viz pumping light ends with a pump specified for heavies as in a Flare KOD

• Seals: Use the right seal system to suit fluids pumped. Light HC may leak in seal system designed for heavies. Seal system requires attention and maintenance. If you see a pool of liquid near a pump, check for seal damage. Seal leaks quickly get worse and lead to fire

• Seals: Propane Circulation Pump Seal failure. PDA unit destroyed

• Seals: Olefins plant seal leak ignored. Counting on prevailing wind direction/ dispersion, production was continued. Wind direction changed and leak size increased. Unconfined Vapor Cloud Explosion

• Seal: LPG pump seal leak. Pump tripped and isolated with suction MOV and discharge closed. Suction spec blinded. After seal replacement, spec blind was removed. Unknown to operators, suction MOV was opened before suction flange bolts were tightened. LPG leak and fire

• Seal: Excessive axial movement of Vacuum Residual Column Bottoms centrifugal pumps resulted in primary seal faces to separate during rotation and gradually fail due to solid particle contamination of the faces causing wear and seal leakage failures. Abdulrahman (Alkhowaiter in LinkedIn)

• Pump strainer maintenance. Block valve failure. Oil spill that auto-ignited and destroyed VBU. Fire spread by FW application 

• Pulsation Dampener Failures: (1) dampener disconnected due to excessive vibration, spraying condensate on nearby heater treater exhaust stack. Ignition. Protect hot piping from liquid spill or leak (2) After dampener failed, bladder filled with pumped fluids. As ambient was -35°C, fluid froze and dampener shell exploded, shrapnel pieces that damaged pump house (3) Similar, N2 charged dampener and pump froze on low ambient temperature. Dampener failed and N2 bladder exploded. Caution: Avoid freezing issues in cold climate

• HP LPG Recip: Failure of gland packing studs. Leak and fire. Missing: F&G; ESDs and ventilated location

• Ethyl chloride reactor vessel circulation pump. Ethyl chloride, mix of a liquefied flammable gas HCl, a toxic and corrosive gas. Leak due to corroded discharge flange and/or failure of discharge flexi pipe. Have remote SDV with significant inventory + proper drainage slope

• FPSO: Condensate pumped by Recip Pump with discharge valve closed. Leak. Leaked HC caught fire due to static current developed by fire hose water sweep action

• Water pumps have exploded, when ran with inlet and outlet closed. Pumped energy heated up trapped water with high thermal expansion. Take care of auto-start / remotely switched on pumps

• Butane pump blocked with hydrate was cleared with a steam hose. Released butane was ignited by a furnace 40m away. Explosion. WWW